KR0148772B1 - Floppy disc for magnetic head cleaning - Google Patents

Abstract

The present invention relates to a floppy disc for magnetic head cleaning, comprising: a magnetic head cleaning floppy disk having a coating layer for cleaning a magnetic head on a base film, wherein the coating layer is a γ-Fe ₂ O ₃ magnetic material, Disclosed is a floppy disk for magnetic head cleaning comprising 100 to 300 wt% of a high hardness abrasive and 9 to 15 wt% of nonmagnetic carbon based on the magnetic material, and having a centerline average surface roughness of 15 to 30 nm.

The cleaning floppy disk of the present invention not only has excellent magnetic head cleaning performance, but can also be used as a magnetic recording and reproducing medium.

Description

Floppy disk for magnetic head cleaning

The present invention relates to a magnetic head cleaning floppy disk, and more particularly, to a magnetic head cleaning floppy disk capable of removing contamination of the magnetic head and having a function as a magnetic recording medium equivalent to the floppy disk for magnetic recording and reproducing. .

The floppy disk used in the floppy disk device (FDD) is a magnetic recording technique applied to a ferromagnetic powder such as γ-Fe ₂ O ₃ and a resin binder such as vinyl chloride on a nonmagnetic support such as polyethylene terephthalate (PET). The mixture has a magnetic film formed by application.

The floppy disk has a structure in which the magnetic head rotates and records and reproduces a track of a certain area which is concentric, and therefore, physical characteristics such as running resistance against friction and abrasion and durability should be good. It is therefore common to add lubricants such as conductive carbon, nonmagnetic particulates such as high-strength abrasives, and fatty acid esters to the floppy disks to reduce wear or friction at the interface of the magnetic head and floppy disks.

However, when the floppy disk is used for a long time, part of the coating layer is gradually dropped due to contact with the magnetic head, friction, and the like, and adheres to the surface of the head. This results in severe head contamination which makes recording and playback impossible. Therefore, cleaning should be performed regularly to remove foreign substances attached to the head.

The magnetic head used for the FDD is precisely embedded in the head support device, and the double-sided head is used simultaneously to correspond to the floppy disk having the magnetic layer formed on both sides of the support to increase the storage capacity. You need a floppy disk for cleaning.

There are two methods of magnetic head cleaning method: wet method to remove the contamination of the magnetic head by dissolving power such as alcohol by using fibrous porous sheet containing cleaning solution such as alcohol, and to remove the head contamination by polishing force on the cleaning disk. Dry methods are used.

Among them, a method of manufacturing a conventional dry cleaning floppy disk is a hard abrasive such as α-Al ₂ O ₃ , Cr ₂ O ₃ and α-Fe ₂ O ₃ , nonmagnetic carbon, lubricant, There is a method of coating a mixture of vinyl chloride and urethane resin and the like and manufacturing it to have hundreds of projections at the centerline surface roughness. In general, the floppy disk for magnetic head cleaning manufactured by this method has enhanced abrasiveness and surface roughness of the abrasive coating layer in order to improve the cleaning effect. Therefore, using such a cleaning floppy disk is likely to damage the magnetic head. In order to solve such a problem, techniques for reducing excessive abrasive force of only an abrasive by manufacturing by mixing an abrasive and a magnetic substance are disclosed in Japanese Patent Laid-Open No. 63-279414.

As can be seen from the above, the conventional cleaning floppy disk merely serves to decontaminate the magnetic head.

In order to record and play back data using a floppy disk for magnetic head cleaning, it must first be formatted in FDD. For this purpose, the magnetic head cleaning floppy disk must be able to maintain at least 45% or more of the output current from the magnetic head, and its characteristics must be close to the requirements of the magnetic recording / reproducing floppy disk.

An object of the present invention is to provide a cleaning floppy disk capable of removing contamination of a magnetic head and at the same time recording and reproducing data.

In order to achieve the above object, in the present invention, in the floppy disk for magnetic head cleaning in which a coating layer for cleaning the magnetic head is formed on the base film, the coating layer is based on the γ-Fe ₂ O ₃ magnetic body and the magnetic body. A floppy disk for magnetic head cleaning is provided, which comprises 100-300% by weight of a hard abrasive and 9-15% by weight of nonmagnetic carbon, and has a centerline average surface roughness of 15-30 nm.

In the floppy disk for magnetic head cleaning according to the present invention, polyesters such as polyethylene terephthalate, polyolefins such as polyethylene and polypropylene, celluloses such as cellulose triacetate and cellulose diacetate can be used for the base film. Vinyl resins such as derivatives, polyvinyl chloride and polyvinylidene chloride, and the like, and polyethylene terephthalate (PET) is particularly preferable.

Υ-Fe ₂ O ₃ magnetic material has a Morse hardness of 5 or more, a coercive force of 600 Oe or more, a specific surface area of 20 m 2 / g or more, and having a needle structure may have its own polishing properties, magnetic properties necessary for recording and reproducing. desirable.

In addition, α-Al ₂ O ₃ , Cr ₂ O ₃ and α-Fe ₂ O ₃ and the like may be used as the high hardness abrasive, and among these, in particular, the hardness of morse is 9 or more, and the specific surface area is in the range of 9-16 m 2 / g, Preference is given to Cr ₂ O ₃ abrasives having an average particle size of 0.3 to 0.4 μm.

The nonmagnetic carbon is preferably 16 to 40 mu m in average particle size and 50 to 950 m 2 / g in specific surface area.

In addition to the magnetic body and the abrasive, the cleaning floppy disk of the present invention may be added a lubricant, a resin binder, a curing agent, a dispersant and the like as necessary.

If the above conditions are satisfied, proper cleaning is performed while the program is executed for a certain time to prevent damage to the magnetic head.

The surface roughness of the coating layer affects the output voltage, the output stability and the cleaning stability which are reproduced in the magnetic head and depends on the calendering process conditions such as the content of the abrasive, the temperature, the linear pressure and the processing speed. Generally, gradually increasing the amount of abrasive while maintaining the surface roughness decreases the magnetic flux density of the coating layer, decreases the regeneration characteristics, and increases the damage ratio of the head, but increases the cleaning effect. On the other hand, if the surface roughness is gradually increased while maintaining the content of the abrasive, regeneration output becomes unstable and errors frequently occur, but the cleaning effect is greatly increased. Therefore, in order to improve the cleaning performance, to maintain a minimum output of 45% or more, and to be able to record and reproduce a certain amount of data, 100 to 300% by weight of abrasive and 9 to 15 of non-magnetic carbon are required based on magnetic material. It should be added in weight percent and have a surface roughness in the range of 15 to 30 nm under these conditions.

Hereinafter, the method for manufacturing a cleaning floppy disk of the present invention will be described in detail.

Γ-Fe ₂ O ₃ magnetic material, ferromagnetic powder, Cr ₂ O ₃ , 100-300 wt. Is dispersed in a solvent such as methyl ethyl ketone, toluene and cyclohexanone to prepare a dispersion. This dispersion is applied to the polyethylene terephthalate film having a thickness of about 75 μm and a surface roughness of 15 nm at 2 to 5 μm. After the magnetic-free orientation treatment and drying, the same treatment is applied to the opposite side of the coating layer, and the appropriate surface roughness in the range of 15 to 30 nm is obtained through a calendering process at a temperature of 50 to 100 ° C. and a linear pressure of 50 to 200 kg / cm. An application layer is formed so that it may have.

Hereinafter, the present invention will be described in detail by Examples and Comparative Examples, but the present invention is not limited thereto.

Performance evaluation of the magnetic head cleaning floppy disks produced by Examples and Comparative Examples of the present invention was carried out in the following manner.

(1) Centerline average surface roughness (Ra)

Measurements were made using an optical non-contact three-dimensional surface roughness meter from WYKD.

(2) Track average regeneration voltage (TAA) and other characteristics

Measured using a floppy disk evaluation device ML-5000 (US Media Logic, Inc., built-in FDD for Sony SOF52W 3.5 2DD), and the input current of the magnetic head is IF (125㎑) on the outermost track 00 track. The tracks were recorded and played back at a frequency of 2F (250 kHz) on the track 79, and are expressed in% relative to the PTB reference value built into the evaluator.

(3) cleaning performance

The contaminated magnetic head is inserted in a Samsung 3.5 2HD SFD32ID / T type FDD that has been modified to run continuously on a power supply, has been run more than 3 million times, and then connected to a PC to play a normal floppy disk with recorded data. Can't magnetic head.

The FDD is an amplifier envelope of a magnetic head contaminated using an FDD exercise (SK-472, manufactured by Tokyo Engineering Co., Ltd.) and an oscilloscope (VP-5739A, manufactured by National Co., Ltd.) in a range of 40 to 80% of the pre-contaminated head measurement value. The waveform is modulated.

The cleaning performance was measured by inserting a cleaning disk into the FDD in which the contaminating head was built, and repeating the format command to compare the number of commands until the disk was normally formatted without a bad section. In FDD, the format check time is indicated as G for 1 time in 25 seconds and within 1 to 3 times, M for 4 to 7 times, and B for 7 times or more. These are abbreviations for Good, Middle, and Bad, respectively.

The cleaned heads used an FDD exercise and an oscilloscope to restore the Amplitude Envelope to over 80% of the head precontamination measurement.

(4) head damage degree

After the cleaning disk was put in the FDD, the degree of scratch damage of the head was observed under an optical microscope.

Example 1

Each compound was mixed and dispersed at the composition ratio to apply a magnetic paint on both sides of the nonmagnetic support, and after drying, a coating layer having a thickness of 2.5 μm was formed. A floppy disk for cleaning 3.5 2DD (post-format capacity 720KByte) was prepared through a calendering process at a temperature of 65 ° C. and 100 kg / cm.

Example 2

A floppy disk for cleaning was prepared in the same manner as in Example 1 except for calendaring at 75 ° C. and 150 kg / cm.

Comparative Example 1

A floppy disk for cleaning was prepared in the same manner as in Example 1 except that the mixed amount of the Cr ₂ O ₃ abrasive was 400 g instead of 250 g.

Comparative Example 2

A floppy disk for cleaning was prepared in the same manner as in Example 1 except that the mixed amount of the Cr ₂ O ₃ abrasive was 70 g instead of 250 g.

Comparative Example 3

A floppy disk for cleaning was prepared in the same manner as in Example 1, without using the Cr ₂ O ₃ abrasive.

As can be seen from Table 1, Example 1-2, in which the abrasive was added at 100 to 300% by weight based on the ferromagnetic material and the surface roughness was adjusted within the range of 15 to 30 nm, showed excellent cleaning performance and It can be seen that data can be recorded and reproduced by maintaining the track average reproducing voltage (TAA) at 45 to 55% without damage.

In Comparative Example 1 having a massager content of 400%, the cleaning performance was excellent, but the head was damaged due to excessive surface irregularities. In Comparative Example 2, in which the abrasive content was less than 100%, the cleaning performance was poor. In addition, in Comparative Example 3 in which the abrasive was not used at all, the surface roughness was flat to about 14 nm, resulting in poor cleaning performance.

Table 2 is a table showing the general characteristics of the cleaning floppy disk prepared according to Example 1. From this table, it can be seen that all characteristics except for output are close to the ranges required for recording and re-writing floppy disks.

As can be seen from the above, the cleaning floppy disk of the present invention has excellent magnetic head cleaning performance and can be used as a magnetic recording and reproducing medium.

Claims (8)

A floppy disk for magnetic head cleaning having a coating layer for cleaning a magnetic head on an upper portion of a base film, wherein the coating layer is a γ-Fe ₂ O ₃ magnetic material and a high hardness of 100 to 300 wt% based on the magnetic material A floppy disk for magnetic head cleaning, comprising an abrasive and 9-15% by weight of nonmagnetic carbon and having a centerline average surface roughness of 15-30 nm. The floppy disk for magnetic head cleaning according to claim 1, wherein the base film is one selected from the group consisting of polyesters, polyolefins, cellulose derivatives, and vinyl resins. The floppy disk for magnetic head cleaning according to claim 1, wherein the coating layer has a thickness of 2 to 5 mu m. The floppy disk for magnetic head cleaning according to claim 1, wherein the γ-Fe ₂ O ₃ magnetic material has a specific surface area of 20 m ₂ / g or more, a MOS hardness of 5 or more, an antimagnetic force of 600 Oe or more, and a needle structure. . The floppy disk for cleaning according to claim 1, wherein the high hardness abrasive is selected from the group consisting of α-Al ₂ O ₃ , Cr ₂ O _3, and α-Fe ₂ O ₃ . The magnetic floppy disk for magnetic head cleaning according to claim 5, wherein the high hardness abrasive is Cr ₂ O ₃ . 7. The floppy disk for magnetic head cleaning according to claim 6, wherein the Cr ₂ O ₃ abrasive has a MOS hardness of 9 or more, a specific surface area in the range of 9 to 16 m 2 / g, and an average particle size of 0.3 to 0.4 m. . The floppy disk for magnetic head cleaning according to claim 1, wherein the non-magnetic carbon has an average particle size of 16 to 40 µm and a specific surface area of 50 to 950 m 2 / g.